The present invention generally relates to a display pattern preparing system and in particular a system for forming picture element series data for raster from data for contour control for the sake of formation and display of picture images.
In the conventional art, a master for printed wiring board wiring is drawn by obtaining data of contour control from a design drawing and then moving in accordance with the data a mechanical head such as of an X-Y plotter in a vector fashion over a plane on which the master is to be formed. This method, however, is defective in that several tens of hours are required for drawing a master of a large area and a high density.
Although the time may be radically shortened if a master is drawn and displayed by way of raster-scanning using an electro-optical means, there is required a system for forming picture elements series data for raster from the contour control data. Disclosed in U.S. Pat. No. 3,812,491 to C. G. Barraclough entitled "Raster-scanned Display Devices" is a device wherein an image is formed electrically and a video signal corresponding to the image is supplied to a raster-scanned display unit such as CRT. This device, however, requires calculation in terms of vectors to produce a picture element series data and has no storage function to memorize a given pattern, thus giving rise to prolonged calculations. Especially, for complicated patterns, the device of extremely sophisticated is required. Another prior art is known in which a pattern to be displayed is directly stored in a memory. Obviously, this prior art requires a large number of memories to deal with a complicated pattern and hence becomes expensive.